If you plan on performing with an acrylic or plastic ball.
Then you need to practice with that.
The issue is that people have hurt themselves with 4" or 100mm
acrylics when doing behind the neck and around the body work. Also
head stalls and head throws.
I am a persons that practices or plays with everyball I can get my hands on.
So if I have a squishy ball I use that when doing things that can
cause a knock out or concusion(sp?). Then I will move to a metal or
plastic ball when I am ready.
The metal or plastic has a more illusionary effect over the squishies.
The only word of advise is to make sure to use a perfectly round ball.
Don't use bean bags and such. As you mention they are hard. They
also don't teach as well, in my opinion.
Just because a squishy is squishy doesn't make it easier. The moves
are just as hard and sometimes harder. Plastic and metal are just
more dangerous for certain things. I should say EXTREME.
-RS TOCJ RS@CJ.C W.RS.C